PHP - Add level to multidimensional array

Question

I have an multidimensional array and I want to add a key and value to every array within the multidimensional array. The value has to be the level of how deep the array is within the multidimensional array.

For example:

Array(
    [0] Array
        (
            [id] 1
            [parentid] null
            [0] Array
                (
                    [id] 101
                    [parentid] 1
    [1] Array
        (
            [id] 2
            [parentid] null
            [0] Array
                (
                    [id] 161
                    [parentid] 2
                    [children] Array
                        (
                            [0] Array
                                (
                                    [id] 300
                                    [parentid] 161
                                 )

Expected output:

Array(
    [0] Array
        (
            [id] 1
            [parentid] null
            [level] 1
            [0] Array
                (
                    [id] 101
                    [parentid] 1
                    [level] 2
    [1] Array
        (
            [id] 2
            [parentid] null
            [level] 1
            [0] Array
                (
                    [id] 161
                    [parentid] 2
                    [level] 2
                    [children] Array
                        (
                            [0] Array
                                (
                                    [id] 300
                                    [parentid] 161
                                    [level] 3
                                 )

What have you tried to get this done? It should not be that difficult — Nico Haase, Apr 03 '18 at 08:43
You can check there :- https://stackoverflow.com/questions/8587341/recursive-function-to-generate-multidimensional-array-from-database-result/8587437#8587437 — nageen nayak, Apr 03 '18 at 08:57

Tschallacka · Accepted Answer · 2018-04-03T19:41:23.040

You basically want to use a recursive function that works with a reference to an array.

By using a parameter &$foo with the & in front of it, you're designating it as a reference to that object.

In the case of an array it will not make a copy of the modification, but perform the modification on the original passed array.

EDIT added suggestion of Yoshi in the comments to pass &value as reference too.

See it live: https://ideone.com/NhKABF

<?php
$array = [
    'hello' => 'world',
    'doing' => [
        'hello' => 'universe',
        'going' => [
            'hello' => 'existence'
         ],
        'moving' => [
            'answer' => 42,
        ]
    ]
];
function levelUp(&$array, $level = 1) 
//               ^-- See that one? that's the  magic.
{
    $array['level'] = $level;

    foreach($array as $key => &$value) {
    //                        ^-- important to add that & here too
        if(is_array($value)) {
            levelUp($value, $level + 1);
        }
    }
}
levelUp($array);
var_dump($array);

Small thing: I think the OP wants the `level` field set to the data's nesting level, not the `id` field. Otherwise great answer. — Mulan, Apr 03 '18 at 16:31

score 0 · Answer 2 · answered Apr 03 '18 at 08:58

0

function buildTree(array $elements, $parentId = 0) {
$branch = array();

foreach ($elements as $element) {
    if ($element['parent_id'] == $parentId) {
        $children = buildTree($elements, $element['id']);
        if ($children) {
            $element['children'] = $children;
        }
        $branch[] = $element;
    }
}

return $branch;

}

$tree = buildTree($rows);

answered Apr 03 '18 at 08:58

nageen nayak

1,262
2
18
28

I think it will help you. – nageen nayak Apr 03 '18 at 09:01
Obviously, because otherwise you wouldn't have posted it ;) – Nico Haase Apr 03 '18 at 09:01
I use this function to build my tree structure. But I've no idea how to add the current level of the array to the array. – Nibboro Apr 03 '18 at 09:02
Have you store level in DB?? – nageen nayak Apr 03 '18 at 09:04
No, the level is not stored in the database yet. Im trying to add the level in the array and want to use that array to insert the data in the database. – Nibboro Apr 03 '18 at 09:07
Can you please post your database table structure so that we can give you best answer. – nageen nayak Apr 03 '18 at 09:09
I am using same array but i store level of that node and get array from DB and then make child parent relationship. – nageen nayak Apr 03 '18 at 09:11
The content of the array in the example, is build from data that comes from multiple database tables. – Nibboro Apr 03 '18 at 09:15

Ramy Herrira · Answer 3 · 2018-04-03T09:15:39.473

0

I don't know if it's relevant but why not use a library like BlueM/Tree ?
It has features built for this kind of problems.

// Get a node's ID
$id = $node->getId();

// Get the node's hierarchical level (1-based)
$level = $node->getLevel();

edited Apr 03 '18 at 09:15

answered Apr 03 '18 at 09:02

Ramy Herrira

574
10
13

May be but i have not use yet that library. – nageen nayak Apr 03 '18 at 09:13

PHP - Add level to multidimensional array

3 Answers3